Lifting columns are known from practice and comprise a frame with a carrier that is connected to a drive for moving the carrier upwards and downwards. In the ascent mode, hydraulic oil is pumped to a cylinder for lifting the carrier with the vehicle. In the descent mode, the carrier with the vehicle is lowered and hydraulic oil returns to the reservoir. Such prior art lifting system is disclosed in U.S. Patent Application Publication No. 2006/0182563, which is incorporated herein by reference.
Mobile lifting columns that are known from practice often comprise a pallet truck mechanism for displacing or positioning the lifting column. A problem associated with such conventional mechanism is that it may unintentionally displace with the lifting column rolling over its wheels while carrying a load. U.S. Pat. No. 5,911,408 of the same applicant discloses the use of a balance connecting a drive and a counter drive, for example including a gas spring. This requires different configurations for different types of lifting columns. This results in a restricted flexibility for generic application of such pallet truck mechanism with different types of lifting columns. In addition, the conventional pallet truck mechanism involves a relatively high number of parts to enable displacement/positioning of the lifting column.
Another problem is the lack of sufficient space when positioning the lifting columns with a conventional pallet truck mechanism. Such conventional mechanisms require sufficient space for manoeuvring the lifting column. This is not always available in a workshop such that positioning the column takes more time and/or may result in damage to the column or its surroundings.
An object of the present invention is to obviate or at least reduce the aforementioned problems associated with positioning/displacing a mobile lifting column.